Enhancing protective immunity effects of nucleic acid vaccines against Schistosoma japonicum infection through electroporation in vivo / 中国血吸虫病防治杂志

ABSTRACT

Objective To enhance the protective immunity effects of nucleic acid vaccines against Schistosoma japonicum infection by electroporation(EP)in vivo in infected BALB/c mice.Methods Plasmids and proteins for immunization were prepared and diluted in no bacterial saline solution to final concentration of 1.5 mg/ml.pcDNA3.1-SjC23,pcDNA3.1-SjCTPI,pcDNA3.1-(CDR3)6 plasmid DNAs were mixed by equal volume to form the cocktail DNA vaccine,and also mixed with recombinant proteins SjC23-HD,SjCTPI,and NP30 by equal volume to form the cocktail protein vaccine.Seventy female BALB/c mice of 4-5 weeks old were randomly divided into 5 groups(A,B,C,D,E).In Group A(control group),each mouse was immunized with 100 ?l saline solution by intramuscular(i.m.);in Group B(pcDNA3.1/EP control group),each mouse was immunized(i.m.)with 100 ?l pcDNA3.1 followed by EP in vivo for three times at week 0,3,6;in Group C(pcDNA3.1/EP plus cocktail protein vaccine group),each mouse was immunized(i.m.)with 100 ?l pcDNA3.1 followed by EP for three times at week 0,3,6 and boosted with 100 ?l cocktail protein vaccine plus 100 ?l FCA by subcutaneous at week 9;in Group D(cocktail DNA vaccine/EP group),each mouse was immunized(i.m.)with 100 ?l cocktail DNA vaccine followed by EP for three times at week 0,3,6;in Group E(cocktail DNA vaccine/EP plus cocktail protein vaccine group),each mouse was immunized(i.m.)with 100 ?l cocktail DNA vaccine followed by EP for three times at week 0,3,6 and boosted with 100 ?l cocktail protein vaccine plus 100 ?l FCA by subcutaneous at week 9.Four weeks after the last DNA immunization or two weeks after protein boosting,all the mice were challenged with(40?1)cercariae of Schistosoma japonicum by abdominal skin penetration.Forty-two days post-challenge,the mice were sacrificed and perfused,and the numbers of recovered worms and eggs in liver were counted.The blood was collected from the tail veins of all the mice two days before the first immunization and challenge,respectively,the serum was prepared for detection of IgG,IgG1 and IgG2a.Two days before the challenge,the spleen cells of two mice from each group were cultured and stimulated with ConA and soluble egg antigen(SEA),and the supernatant was collected for detection of IL-2,IL-4 and IFN-? by flow cytometre.Results The worm reduction rates in Group C,D and E were 18.09%,45.00% and 57.09%,respectively,compared with the control group.The worm reduction rates in Group D and E were significantly higher than that in Group C(P